Sunday, February 27, 2011

Accessibility: Intermediate

Disclaimer: My PI is an author on this paper.

There is a lot of variability in outcomes for children diagnosed with dyslexia. Some children improve greatly over time, while others don't. Today, we're looking at a paper that asks whether it's possible to predict improvement in children with dyslexia.

Fumiko Hoeft and colleagues scanned children with and without dyslexia while performing a word rhyme task. They also tested the children on several reading measures. Two and half years later, they retested the children again on the same reading measures. Some of the children improved, while others didn't . The question then, is whether there is something from the brain scans or test scores in the first session that can predict performance 2 1/2 years later.

The researchers found two brain measures that predicted improvement in reading skills: greater white matter integrity in the right superior longitudinal fasciculus, and activation in the right inferior frontal gyrus during the rhyming task. Note that these regions are not your typical language regions. In fact, they are the right hemisphere counterparts of language processing regions in typical readers. Also, these didn’t correlate with reading improvement in control readers.This suggests that rather than imitating what typical readers are doing, the dyslexics who improve are bringing in compensatory mechanisms.

So if we have a dyslexic child, how accurately can we predict future improvement? The researchers found that brain data from those two regions by themselves predicted reading gains with 72% accuracy. When the researchers used data from the entire brain, they predicted reading gains with 90% accuracy. (Chance would be 50%. The researchers were trying to predict whether a child’s improvement was below or above the median improvement for the entire group.)

These results are an interesting case of brain data giving us more information the behavioral measures. None of the behavioral measures predicted which children would improve, but the brain data did.

One might ask how useful these results would be for dyslexics. On the one hand, any information is helpful. On the other, if you are in the group predicted to not show improvements, would you really want to know? One good thing about this type of research is that perhaps if we keep going in this direction, we might be able to not only predict improvement, but predict improvement to different types of interventions, thus leading to better treatment.

Interesting post. But given the research around plasticity, doesn't it seem that the correct intervention could make a HUGE difference? I'm kind of surprised that studies don't control for that. I teach early-reading enrichment, and I have two students right now who show signs of dyslexia. However, with phonics based intervention, I have seen DRAMATIC improvement in both of them. I don't worked for a phonics company or anything, but I am coming to the conclusion that, when caught early enough, rigorous intervention can make a huge difference in a child's capacity for learning.

(btw, I'm not anonymous, I just don't know how to post with the proper url or whatever. My email is katebloomer@gmail.com

Anonymous -- Depressingly, when the authors went back to look at the effect of intervention in this data set, it didn't seem to make a difference compared to those who didn't get intervention. Could be that those families just didn't choose interventions that worked for their kids.